1. Field
The following description relates to a technology for automatically controlling lighting.
2. Description of Related Art
One of the most realistic and effective ways to reduce energy consumption due to the use of lighting would be switching off the lamps or turning off the electronic devices not in use in vacant areas, for example, office rooms, classrooms, or conference rooms. The purpose of this method is to minimize the reduction of usable power. To this end, in the above method, a designated lighting scene may be recreated according to the presence or absence of a person in an area of interest or the time schedule for lighting control.
In addition, it has been suggested to control the brightness of a fluorescent lamp or a dimmable lamp so as to provide a specific level of illuminance. Yet, in another method, an illuminance level (lux) that is measured in real-time is compared with a desired illuminance level which is set by a micro controller, and the brightness of a lamp is automatically adjusted. When sunlight is utilized as a lighting source, it may be advantageous in that as much energy can be saved as is consumed by luminaires. However, the illuminance modeling of sunlight is not simple due to a number of variables, such as the season, weather, indoor building structure, and light transmittance through a window, and the like.
As an archetypal illuminance modeling method, illuminance L at the moment when light from a luminaire is irradiated in free space is calculated by Equation 1 below. FIG. 1 is a graph plotting Equation 1.Illuminance L=Luminous intensity(cd)/(r)2,[Lux]  (1),
where r denotes a distance from a luminaire to an illuminance measurement device, luminous intensity refers to the intensity of light emitted from the luminaire, which varies depending on the type of luminaire. In reality, even when the same luminaire is used, the illuminance at the same point of interest may vary depending on the surroundings of the point, for example, a reflector located near said point.